The present invention relates to internal combustion engines and, more particularly, to an internal combustion engine that is significantly more efficient than those known heretofore.
Internal combustion piston engines have been familiar and ubiquitous since the days of Otto and Diesel. These engines suffer from several widely recognized deficiencies. One is that their thermal efficiencies are far less than their theoretical efficiencies according to the second law of thermodynamics. Up to 30% of the heat released by fuel combustion is absorbed by the engine cooling systems. Another 30% is devoted to engine operation, including compressing air or an air-fuel mixture in the cylinders of these engines. From 5% to 20% of the available energy may be wasted because of incomplete combustion of hydrocarbon fuels. The net result is that these engines generally have overall efficiencies between 32% and 42%.
Another deficiency of these engines is that their exhausts tend to contain toxic substances: carbon particles and carcinogenic hydrocarbons because of incomplete combustion, and nitrogen oxides formed at the high (1800.degree. C. to 2000.degree. C.) combustion temperatures that characterize these engines. A third is that they provide power by transforming the reciprocating motion of their pistons to the rotary motion of their crankshafts. When the fuel-air mixture in a cylinder of an internal combustion engine explodes, the piston is at or near top dead center. At this position, the moment arm, across which the rod connecting the piston to the crankshaft transfers force to the crankshaft, is close to zero. Therefore, the piston exerts minimal torque on the crankshaft. As the piston moves down from top dead center, the moment arm through which the piston transfers force increases, but in the meantime the combustion gases expand somewhat, losing some of their propulsive force, so that the maximum torque exerted on the crankshaft is less than the maximum torque that could be exerted if the force of the piston could always be transferred to the crankshaft at maximum moment arm. Several attempts have been made to address some of these deficiencies. Ferrenberg et al. (U.S. Pat. No. 4,928,658) use a heat exchanger to preheat the input fuel and air of an internal combustion engine with some of the heat of the exhaust gases. Loth et al. (U.S. Pat. No. 5,239,959) ignite the fuel-air mixture in a separate combustion chamber before introducing the burning mixture to the cylinder, in order to attain more complete combustion and inhibit the formation of nitrogen oxides. Forster (U.S. Pat. No. 5,002,481) burns a mixture of fuel, air and steam. This mixture burns at a relatively low temperature of about 1400.degree. C., and nitrogen oxides are not formed. Gunnerman (U.S. Pat. No. 5,156,114) burns a mixture of hydrocarbon fuel and water, but requires a hydrogen-forming catalyst to achieve the same power with his mixture as with ordinary gasoline. Each of these prior art patents addresses only one of the defects of reciprocating internal combustion engines. None addresses the problem in its totality.
U.S. Pat. No. 5,797,366 describes an engine that further addresses the outstanding deficiencies of existing internal combustion engines. In this engine, a mixture of fuel, air and steam is burned in one or more combustion chambers, each combustion chamber being defined by a toroidal combustion chamber housing, a piston and a valve. The mixture is burned at a temperature between about 1400.degree. C. and about 1800.degree. C., thereby minimizing the formation of nitrogen oxides and other pollutants while reducing the heat lost to conduction and radiation through the engine walls. The axis of rotation of the power shaft of the engine is perpendicular to the plane of the combustion chamber housing. The piston is connected to the power shaft of the engine, and the force of the piston always is applied to the power shaft at a constant moment arm perpendicular to that axis of rotation, so that maximum torque is imposed on the power shaft.
In the toroidal engine of U.S. Pat. No. 5,797,366, the volume of the combustion chamber increases as the burning mixture pushes the piston away from the valve. This increase in volume, before the mixture is entirely burned, tends to decrease the thermodynamic efficiency of this engine.
There is thus a widely recognized need for, and it would be highly advantageous to have, an internal combustion engine that further approaches its theoretical thermal efficiency while emitting minimal pollution.